An occupant of a vehicle may want a device holder to hold an electric device such as a smart phone and a tablet so that he or she can use the electronic device or view the content displayed without holding the electronic device by hands. One area to place the device holder is a back of a seat. It can be a challenge to design the device holders fitted into a seat back because the seats can have various configurations and the space between the seat back and a seat behind is limited. Further, the existence of varied sizes of the electronic devices demands a universal device holder for various sizes of the electronic devices. The inventors have recognized that it is desirable to have a device holder that can fit the different configurations of the seats and hold the electronic devices with different sizes.